1. Technical Field
The present invention relates to an electro-optical device substrate used for manufacturing an electro-optical device, such as a liquid crystal device, and to an electro-optical device manufactured using the electro-optical device substrate. In addition, the present invention relates to a method of testing the electro-optical device.
2. Related Art
In general, this type of electro-optical device includes an electro-optical panel for displaying images and a driving circuit. The driving circuit is mounted on a substrate having an electro-optical panel thereon.
The electro-optical device (including the driving circuit when the driving circuit is mounted therein) is generally tested to detect defects, for example, during manufacture, after manufacture, prior to shipping, when the device is examined after use, and when the device is out of order. For example, the electro-optical device is driven in an incomplete state, such as before mounting the driving circuit, or in the state of an electro-optical panel to display a testing image, and then the testing is performed based on the suitability of the testing image. Alternatively, a testing circuit is incorporated into the electro-optical device, and signals of the testing circuit are monitored when driving the device, thereby testing the electro-optical device (see Japanese Unexamined Patent Application Publication No. 10-260391).
However, in the electro-optical device employing, for example, a multiplex method, which is called a hybrid type, it is difficult to perform the testing because the structure of the device becomes complicated.
More specially, in the hybrid-type electro-optical device, a plurality of image signals corresponding to a plurality of data lines in the electro-optical panel are supplied from an external driving circuit. Also, the electro-optical device is driven in the following multiplex method. That is, the image signals are input to each pixel unit of the electro-optical panel, and the input image signals are time-divided into R (red), G (green), and B (blue) components by a demultiplexer. Then, the components are input to three data lines corresponding to three dots constituting one pixel, respectively.
In this case, the number of image signal terminals to which the image signals are input from the outside should be at least a third of the number of the data lines (that is, the number of pixels in the horizontal direction). That is, in the hybrid-type electro-optical panel, in general, the number of image signal terminals is up to several hundreds.
The number of image signal terminals of the hybrid-type electro-optical panel is considerably larger than the number of image signal terminals of an electro-optical device which is driven by so-called serial-parallel expansion (that is, phase expansion). In the serial-parallel expansion, since each group of L data lines is simultaneously driven by the image signals supplied from L image signal lines (for example, 6, 12, or 24 image signal lines), L image signal terminals are required. That is, several or several tens of image signal terminals are required at most.
In the hybrid-type electro-optical device, the number of image signal terminals is relatively large, and gaps between the image signal terminals are relatively narrow. Thus, when the above-mentioned test is performed by bringing a probe into contact with the image signal terminals, the probe should be positioned with high precision. As a result, it is difficult to perform the test with high accuracy, which results in a low degree of manufacturing efficiency and an increase in testing costs.